Copper foil with carrier, coreless support with wiring layer, and method for producing printed circuit board

ABSTRACT

There is provided a copper foil provided with a carrier exhibiting a high peeling resistance against the developer in the photoresist developing process and achieving high stability of mechanical peel strength of the carrier. The copper foil provided with a carrier comprises a carrier; an interlayer disposed on the carrier, the interlayer having a first surface adjacent to the carrier and containing 1.0 atom % or more of at least one metal selected from the group consisting of Ti, Cr, Mo, Mn, W and Ni and a second surface remote from the carrier and containing 30 atom % or more of Cu; a release layer disposed on the interlayer; and an extremely-thin copper layer disposed on the release layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. application Ser. No.16/397,449, filed Apr. 29, 2019, which is a Continuation of U.S.application Ser. No. 16/080,442, filed Aug. 28, 2018, now issued as U.S.Pat. No. 10,356,915, which is a National stage of International PatentApplication No. PCT/JP2017/006423, filed Feb. 21, 2017, which claimspriority to International Patent Application No. PCT/JP2016/076047,filed Sep. 5, 2016 and Japanese Application No. 2016-037308, filed Feb.29, 2016. The disclosure of each of these applications is incorporatedby reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a copper foil provided with a carrierand a method for manufacturing a coreless support provided with a wiringlayer and a printed wiring board.

BACKGROUND ART

In recent years, multilayer printed wiring boards have graduallyprevailed to meet a decrease in size of and an increase in packagingdensity on the printed wiring board. Such multilayer printed wiringboards have been used for reductions in weight and size of many portableelectronic devices. Requirements for the multilayer printed wiringboards include a further reduction in thickness of the insulatinginterlayer and a further reduction in weight of the wiring board itself.

To meet such requirements, a method for manufacturing a multilayerprinted wiring board by a coreless build-up process has been employed.The coreless build-up process alternately builds up insulating layersand wiring layers without a so-called core substrate into a multilayer.In the coreless build-up process, it has been proposed to use a copperfoil provided with a carrier to facilitate separation between thesupport and the multilayer printed wiring board. For example, PatentDocument 1 (JP2005-101137A) discloses a method for manufacturing apackage substrate for mounting semiconductor devices, comprising bondingan insulating resin layer to the carrier surface of a copper foilprovided with a carrier to form a support and then forming a firstwiring conductor adjacent to the extremely-thin copper layer of thecopper foil provided with a carrier by a process, for example,photoresist processing, pattern electrolytic copper plating, or resistremoval, followed by forming a build-up wiring layer, releasing thesupporting substrate provided with a carrier, and removing theextremely-thin copper layer.

Meanwhile, a copper foil provided with a carrier having anextremely-thin copper layer having a thickness of 1 μm or less has beendesired to miniaturize the embedded circuit as shown in PatentDocument 1. Accordingly, it has been proposed to form an extremely-thincopper layer by vapor deposition to achieve a reduction in thickness ofthe extremely-thin copper layer. For example, Patent Document 2(JP4726855B2) discloses a copper foil with a carrier sheet interposed bya bonding interface layer. The bonding interface layer consists of twosublayers, i.e., a metal sublayer (adjacent to the carrier sheet) and acarbon sublayer (adjacent to the extremely-thin copper layer) and thecopper foil layer was prepared by forming a first copper layer having athickness of 10 nm to 300 nm on the bonding interface layer by physicalvapor deposition and further forming a second copper layer byelectrolysis. This document also discloses that the metal sublayer ofthe bonding interface layer may be composed of any one of tantalum,niobium, zirconium, nickel, chromium, titanium, iron, silicon,molybdenum, vanadium, and tungsten.

Patent Document 3 (JP4072431) discloses a copper foil provided with acarrier having a surface provided with, in sequence, a chromium releaselayer, an antidiffusion layer readily absorbable light havingwavelengths oscillated by CO₂ gas laser, and an electrolytic copperplating layer, wherein the antidiffusion layer is a single-metal layercomposed of an element selected from the group consisting of nickel,cobalt, iron, molybdenum, tungsten, aluminum, and phosphorus, or analloy layer composed of two or more elements selected from the groupconsisting of nickel, cobalt, iron, chromium, molybdenum, tungsten,copper, aluminum and phosphorus or a metal oxide layer of one or moreelements.

CITATION LIST Patent Documents

Patent Document 1: JP2005-101137A

Patent Document 2: JP4726855B2

Patent Document 3: JP4072431B2

Patent Document 4: JP2015-35551

SUMMARY OF INVENTION

Meanwhile, the use of a coreless build-up method is also examined inFan-Out Wafer Level Packaging (FO-WLP) and Fan-Out Panel Level Packaging(FO-PLP), which are packaging technologies for printed wiring boards. ARedistribution Layer-First (RDL-First) method is one of the packagingtechnologies (see, for example, Patent Document 4 (JP2015-35551A) thatinvolves forming a wiring layer and a build-up wiring layer, asrequired, on the surface of a coreless support, releasing the support asrequired, and then mounting the chip. This method enables imageinspection of the wiring layer on the surface of the coreless supportand each build-up wiring layer stacked thereafter before chip mounting,so that the chip may be mounted only on non-defective portion of eachwiring layer. As a result, the RDL-First method, which does not causewasteful use of the chip, is economically advantageous compared to theChip-First method, which sequentially stacks the wiring layer on thesurface of the chip. Image inspection immediately after the wiring layeris formed on the surface of the coreless support involves processes suchas photoresist processing, electroplating, and photoresist peeling onthe surface of the coreless support, flash etching of the extremely-thincopper layer existing between the wirings as necessary, followed bymounting of electronic elements such as chips as necessary, resulting inbuild-up layer. Mount of an electronic element such as a chip, however,involves heating, so that coreless support likely to warp. To preventthis problem, materials such as glass, ceramics, and low thermalexpansion resins which have a low thermal expansion coefficient (CTE)are considered to be used as carriers. Unfortunately, carriers composedof such a low thermal expansion material are likely to peel off readily.This problem is especially noticeable in the case of a carbon releaselayer. Although a possible countermeasure is to provide a layer forimproving adhesion between the release layer and the carrier, it causesthe peel strength of the carrier to be unstable, precluding stableremoval of the carrier at the time of separation of the corelesssupport. Thus, stable mechanical peel strength of the carrier cannot beachieved. In other words, the mechanical peel strength of the carrier isunstable. Meanwhile, another requirement on the copper foil providedwith a carrier is to exhibit peeling resistance in a photoresistdeveloping step (for example, a step using an aqueous sodium carbonatedeveloper) for forming a wiring layer on the surface of the corelesssupport.

The inventors have found that an interlayer composed of a specificmetal, which is interposed between the carrier and the release layer ofthe copper foil provided with a carrier, can provide a copper foilprovided with a carrier exhibiting a high peeling resistance against thedeveloper in the photoresist developing process and achieving highstability of mechanical peel strength of the carrier.

Accordingly, an object of the present invention is to provide a copperfoil provided with a carrier exhibiting a high peeling resistanceagainst the developer in the photoresist developing process andachieving high stability of mechanical peel strength of the carrier.

According to an aspect of the present invention, there is provided acopper foil provided with a carrier, comprising:

-   -   a carrier;    -   an interlayer disposed on the carrier, the interlayer having a        first surface adjacent to the carrier and containing 1.0 atom %        or more at least one metal selected from the group consisting of        Ti, Cr, Mo, Mn, W and Ni and a second surface remote from the        carrier and containing 30 atom % or more of Cu;    -   a release layer disposed on the interlayer; and    -   an extremely-thin copper layer disposed on the release layer.

According to another aspect of the present invention, there is provideda method for manufacturing a coreless support provided with a wiringlayer, comprising the steps of:

-   -   providing the copper foil provided with a carrier according to        the above aspect as a support;    -   forming a photoresist layer with a predetermined pattern on the        surface of the extremely-thin copper layer;    -   forming an electrolytic copper plating layer on the exposed        surface of the extremely-thin copper layer;    -   peeling off the photoresist layer; and    -   removing an unnecessary portion of the extremely-thin copper        layer by copper flash etching to prepare a coreless support        provided with a wiring layer.

According to another aspect of the present invention, there is provideda method for manufacturing a printed wiring board, comprising the stepsof:

-   -   manufacturing a coreless support provided with a wiring layer by        the method according to the above aspect,    -   forming a build-up layer on a surface having the wiring layer of        the coreless support provided with a wiring layer to prepare a        laminate with a build-up layer;    -   separating the laminate with a build-up layer at the release        layer to prepare a multilayer wiring board including the        build-up layer; and    -   processing the multilayer wiring board to prepare a printed        wiring board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional diagram illustrating an embodimentof a copper foil provided with a carrier of the present invention.

FIG. 2 is a schematic cross-sectional diagram illustrating anotherembodiment of a copper foil provided with a carrier of the presentinvention.

FIG. 3 is a process flow chart for explaining initial steps (steps (a)to (c)) of a method for manufacturing a coreless support provided with awiring layer or a printed wiring board of the present invention.

FIG. 4 is a process flow chart for explaining middle steps (steps (d) to(f)) following FIG. 3 of a method for manufacturing a coreless supportprovided with a wiring layer or a printed wiring board of the presentinvention.

FIG. 5 is a process flow chart for explaining final steps (steps (g) to(i)) following FIG. 4 of a method for manufacturing a printed wiringboard of the present invention.

DESCRIPTION OF EMBODIMENT

Copper Foil Provided with a Carrier

The copper foil provided with a carrier of the present invention isschematically illustrated in FIG. 1. As shown in FIG. 1, the copper foil10 provided with a carrier of the present invention includes a carrier12, an interlayer 14, a release layer 16, and an extremely-thin copperlayer 18 in this order. The interlayer 14 is disposed on the carrier 12and has a first surface adjacent to the carrier 12 and a second surfaceremote from the carrier 12. The first surface contains 1.0 atom % ormore of at least one metal selected from the group consisting of Ti, Cr,Mo, Mn, W and Ni and the second surface contains 30 atom % or more ofCu. The release layer 16 is disposed on the interlayer 14. Theextremely-thin copper layer 18, which is made of copper, is disposed onthe release layer 16. The copper foil 10 provided with a carrier of thepresent invention may further include an optional antireflective layer17 between the release layer 16 and the extremely-thin copper layer 18.These layers may be laminated on the upper and lower surfaces of thecarrier 12 to be symmetric about the carrier 12. The copper foil 10provided with a carrier may have any known layer configuration withproviso that the copper foil 10 provided with carrier is provided withthe interlayer 14 and the optional antireflective layer 17.

Thus, a copper foil 10 provided with a carrier, including an interlayer14 composed of a predetermined metal interposed between the carrier 12and the release layer 16, can provide high peeling resistance againstthe developer in photoresist developing process, high stability ofmechanical peel strength of the carrier, and excellent wiring patternforming ability due to no detachment of the interlayer when the corelesssupport or the carrier is peeled off. Although the mechanism on sucheffect of the interlayer 14 is not clear, the inventors can propose thefollowing reason. Copper constituting the surface remote from thecarrier 12 (i.e., adjacent to the release layer 16) of the interlayer 14can provide a stable releasability due to its lower adhesion to thematerial (for example, carbon) constituting the release layer 16, butcan provide an unstable adhesion and releasability between the surfaceand the carrier (for example, glass or ceramics). In this respect, it isbelieved that 1.0 atom % or more of at least one metal selected from thegroup consisting of Ti, Cr, Mo, Mn, W and Ni contained on the surface(adjacent to the carrier 12) of the interlayer 14 can provideadvantageously excellent release stability and peeling resistanceagainst the developer between the interlayer 14 and the carrier 12.

The material of the carrier 12 may be any one of glass, ceramic, resin,and metal. Furthermore, the form of the carrier 12 may be any one ofsheet, film, plate, and foil. Furthermore, the carrier 12 may be alaminate of materials such as sheets, films, plates, and foils. Forexample, the carrier 12 may function as a rigid support such as a glassplate, a ceramic plate, and a metal plate, or may be in a nonrigidsupport such as a metal foil or a resin film. Examples of the preferredmetal of the carrier 12 include copper, titanium, nickel, stainlesssteel, and aluminum. Examples of the preferred ceramics include alumina,zirconia, silicon nitride, aluminum nitride, and other fine ceramics.Examples of the preferred resin include PET resins, PEN resins, aramidresins, polyimide resins, nylon resins, liquid crystal polymers, PEEKresins, polyimide resins, polyamide-imide resins, polyethersulfoneresins, polyphenylene sulfide resins, PTFE resins, and ETFE resin. Inview of preventing warping of the coreless support by heating duringmount of the electronic element, these materials more preferably have athermal expansion coefficient (CTE) of less than 25 ppm/K (typically 1.0to 23 ppm/K). Examples of such materials include the above-mentionedresins (especially low-thermal-expansion resins such as polyimide resinsand liquid crystal polymers), glass, and ceramics. In view of handlingand flatness during chip mounting, the Vickers hardness of the carrier12 is preferably 100 HV or more, more preferably 150 to 2500 HV. Interms of material satisfying these properties, the carrier 12 ispreferably composed of resin, glass or ceramics, more preferablycomposed of glass or ceramics, most preferably composed of glass. Forexample, the carrier 12 is a glass sheet. The carrier 12 composed ofglass has advantages such as lightweight, low thermal expansioncoefficient, high insulating property, rigidity and a flat surface, sothat the surface of the extremely-thin copper layer 18 can be madeextremely smooth. The glass carrier has further advantages, such as highvisibility contrast with copper plating at the time of image inspectionafter formation of the wiring layer on the surface of the corelesssupport, surface flatness (coplanarity) suitable for mounting anelectronic device, resistance against chemicals in the desmear processof manufacturing a printed wiring board and various plating processes,and separation of the laminate with the build-up layer described laterby a chemical separation process. Examples of the preferred glassconstituting the carrier 12 include quartz glass, borosilicate glass,non-alkali glass, soda-lime glass, aminosilicate glass, and combinationsthereof, particularly preferably non-alkali glass. The non-alkali glassis substantially free of alkali metal and mainly contains alkaline earthmetal oxide, e.g., silicon dioxide, aluminum oxide, boron oxide, and analkaline earth metal oxide, such as calcium oxide and barium oxide, andboric acid. The non-alkali glass has a low stable thermal expansioncoefficient of 3 to 5 ppm/K in a wide temperature range from 0° C. to350° C., so that warp of the glass is advantageously minimized duringmount of a semiconductor chip as an electronic element. The carrier hasa thickness of preferably 100 to 2000 μm, more preferably 300 to 1800μm, most preferably 400 to 1100 μm. The carrier having a thicknesswithin such a range can achieve thinning of the printed wiring board anda reduction in warp during mount of the electronic parts, whilemaintaining adequate strength that does not interfere with handling.

The surface adjacent to the interlayer 14 of the carrier 12 has anarithmetic average roughness Ra of 0.1 to 70 nm, more preferably from0.5 to 60 nm, still more preferably from 1.0 to 50 nm, particularlypreferably from 1.5 to 40 nm, most preferably from 2.0 to 30 nm,measured in accordance with JIS B 0601-2001. Thus, such a carrier havinga smaller arithmetic average roughness can lead to a smaller arithmeticaverage roughness Ra on the surface of the extremely-thin copper layer18 remote from the release layer 16 (the outer surface of theextremely-thin copper layer 18), resulting in a copper foil 10 providedwith a carrier suitable for forming an ultrastructural wiring patternhaving such a fine line/space (L/S) of (13 μm or less)/(13 μm or less)(e.g., 12 μm/12 μm to 2 μm/2 μm) in the printed wiring board.

The surface adjacent to the carrier 12 of the interlayer 14 ispreferably composed of at least one metal M selected from the groupconsisting of Ti, Cr, Mo, Mn, W and Ni from the viewpoint of securedadhesion between the carrier 12 and the interlayer 14. The content ofthe metal M on the surface adjacent to the carrier 12 of the interlayer14 is preferably 1.0 atom % or more, more preferably 3.0 atom % or more,still more preferably 4.0 atom % or more. The metal may be a pure metalor an alloy. The interlayer has no upper limit of the metal content, andthus the upper limit may be 100 atom %. The surface remote from thecarrier 12 of the interlayer 14 is composed of a metal containing Cu.The surface remote from the carrier 12 (i.e., adjacent to the releaselayer 16) of the interlayer 14 has a Cu content of preferably 30 atom %or more, more preferably 40 atom % or more, still more preferably 50atom % or more. The surface has no upper limit of the Cu content andthus may has a Cu content of 100 atom %.

The interlayer 14 has a thickness of preferably 5 to 1000 nm, morepreferably 10 to 800 nm, still more preferably 12 to 500 nm,particularly preferably 15 to 400 nm. This thickness is determined fromthe cross section of the layer with transmission electronmicroscopy-energy dispersive X-ray spectroscopy (TEM-EDX).

The interlayer 14 may have a single layer structure as shown in FIG. 1,or may have a structure of two or more layers as shown in FIG. 2.

According to a preferred embodiment of the present invention, as shownin FIG. 2, the interlayer 14 includes an adhesive metal layer 14 a and arelease assisting layer 14 b. The adhesive metal layer 14 a is disposedon the carrier 12 and is composed of at least one metal selected fromthe group consisting of Ti, Cr, Mo, Mn, W, and Ni. The release assistinglayer 14 b is disposed on the adhesive metal layer 14 a and is composedof copper. Thus, an adhesive metal layer 14 a composed of apredetermined metal and a release assisting layer 14 b disposed in thisorder between the carrier 12 and the release layer 16 of the copper foil10 provided with a carrier can provide high peeling resistance againstdeveloper in the photoresist developing process, and high stability ofmechanical peel strength of the carrier. Although the mechanism by whichthe combination of the adhesive metal layer 14 a and the releaseassisting layer 14 b has the above effect is not clarified, it can bepresumed as follows. Copper constituting the release assisting layer 14b can provide stable releasability due to lower adhesion with thematerial (for example, carbon) constituting the release layer 16, butcan provide an instable adhesion and releasability between the releaseassisting layer and the carrier (for example, glass or ceramics). Inthis respect, it is presumed that the adhesive metal layer 14 ainterposed between the release assisting layer 14 b and the carrier 12provide advantageously excellent release stability and peelingresistance against the developer between the release assisting layer 14b and the carrier 12 and excellent wiring pattern formability bypreventing the detachment of the interlayer accompanied by peeling offof the coreless support or the carrier.

The adhesive metal layer 14 a is preferably composed of at least onemetal selected from the group consisting of Ti, Cr, Mo, Mn, W and Nifrom the viewpoint of secured adhesion between the carrier 12 and therelease assisting layer 14 b, and may be composed of a pure metal or analloy. It is most preferred that the adhesive metal layer 14 a becomposed of Ti because the adhesion of the carrier 12 to the adhesivemetal layer 14 a and the release assisting layer 14 b is secured tosignificantly prevent peeling of the extremely-thin copper layer in theprocess of forming a coreless support wiring layer described later andpeelings of the adhesive metal layer 14 a and the release assistinglayer 14 b, which provides metal adjacent to the carrier when thecoreless support is peeled, which is described later. The metalconstituting the adhesive metal layer 14 a may contain incidentalimpurities derived from, for example, raw material components and thedeposition process. In the case that the product is exposed to theatmosphere after the deposition of the adhesive metal layer 14 a, oxygenmay be incorporated into the product without particular limitation. Theadhesive metal layer 14 a is preferably formed by vapor phase depositionsuch as sputtering. The adhesive metal layer 14 a is particularlypreferably formed by magnetron sputtering with a metal target in termsof improved uniformity of the film thickness distribution. The adhesivemetal layer 14 a has a thickness of preferably 5 to 500 nm, morepreferably 10 to 300 nm, most preferably 18 to 200 nm, particularlypreferably 20 to 100 nm. This thickness is determined from the crosssection of the layer with transmission electron microscopy-energydispersive X-ray spectroscopy (TEM-EDX).

The release assisting layer 14 b is composed of copper. The copperconstituting the release assisting layer 14 b may contain incidentalimpurities derived from, for example, raw material components and thedeposition process. The release assisting layer 14 b may contain atleast one metal selected from the group consisting of Si, Al, Ni, Mn,Mg, Nd, Nb, Ag, Zn, Sn, Bi, and Fe within a content not impairing thereleasability of the carrier. In this case, the release assisting layermay be mainly containing copper. It is accordingly preferred that thecontent of the Cu element in the release assisting layer 14 b be 50 to100 atom %, more preferably 60 to 100 atom %, still more preferably 70to 100 atom %, particularly preferably 80 to 100 atom %, most preferably90 to 100 atom %. In the case that the product is exposed to theatmosphere after or before the deposition of the release assisting layer14 b, oxygen may be incorporated into the product. It is preferred, butshould not be limited, that the adhesive metal layer 14 a and therelease assisting layer 14 b be continuously formed without beingexposed to the air. The release assisting layer 14 b is preferablyformed by vapor phase deposition such as sputtering. The releaseassisting layer 14 b is particularly preferably formed by magnetronsputtering with a copper target in view of the improved uniformity offilm thickness distribution. The release assisting layer 14 b has athickness of preferably 5 to 500 nm, more preferably 10 to 400 nm, mostpreferably 15 to 300 nm, particularly preferably 20 to 200 nm. Thisthickness is determined from the cross section of the layer withtransmission electron microscopy-energy dispersive X-ray spectroscopy(TEM-EDX).

It should be noted that another intervening layer may be present betweenthe adhesive metal layer 14 a and the release assisting layer 14 b.Examples of constituent materials of the intervening layer includealloys of Cu with at least one metal selected from the group consistingof Ti, Cr, Mo, Mn, W and Ni.

According to another preferred embodiment of the present invention, theinterlayer 14 may be an intermediate alloy layer, as shown in FIG. 1. Inother words, the interlayer 14 can have a single-layer structure. Theinterlayer 14 as an intermediate alloy layer is preferably composed of acopper alloy containing 1.0 atom % or more at least one metal M selectedfrom the group consisting of Ti, Cr, Mo, Mn, W and Ni and 30 atom % ormore copper. In detail, it is preferred that the metal constituting theintermediate alloy layer be a copper alloy of a metal M and Cu in viewof compatibility between the secured adhesion of the carrier 12 to theinterlayer 14 and the ease of release to the release layer 16. Amongthem, an alloy of Cu and at least one metal selected from the groupconsisting of Ti, Mo, and Mn is more preferred. The content of the metalM in the intermediate alloy layer is preferably 1.0 atom % or more, morepreferably 3.0 atom % or more, still more preferably 5.0 atom % or more.The metal M content in the intermediate alloy layer has no upper limit,but has preferably 30 atom % or less, more preferably 20 atom % or less.The intermediate alloy layer has a Cu content of preferably 30 atom % ormore, more preferably 40 atom % or more, still more preferably 50 atom %or more. The intermediate alloy layer has no upper limit of the Cucontent, but has a Cu content of preferably 99.5 atom % or less, morepreferably 97.0 atom % or less, most preferably 96.0 atom % or less. Theintermediate alloy layer is preferably formed by vapor phase depositionprocess such as sputtering. It is particularly preferred that theintermediate alloy layer be formed by magnetron sputtering with a copperalloy target from the viewpoint of the improved uniformity of the filmthickness distribution. The intermediate alloy layer has a thickness ofpreferably 5 to 500 nm, more preferably 10 to 400 nm, most preferably 15to 300 nm, particularly preferably 20 to 200 nm. This thickness isdetermined from the cross section of the layer with transmissionelectron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX).Another intervening layer may be present in the intermediate alloylayer. Examples of constituent materials of the intervening layerinclude alloys of Cu with at least one metal selected from the groupconsisting of Ti, Cr, Mo, Mn, W, and Ni.

The release layer 16 facilitates the release of the carrier 12 (which isaccompanied by the interlayer 14), and may be either an organic releaselayer or an inorganic release layer. Examples of the organic componentused in the organic release layer include nitrogen-containing organiccompounds, sulfur-containing organic compounds, and carboxylic acids.Examples of the nitrogen-containing organic compounds include triazolecompounds and imidazole compounds. Examples of the inorganic componentused in the inorganic release layer include at least one metal oxide ofNi, Mo, Co, Cr, Fe, Ti, W, P and Zn, and examples of the layer include acarbon layer. Among these, the particularly preferred release layer 16is mainly composed of carbon, from the viewpoint of releasability andfilm forming property, more preferably composed of carbon orhydrocarbon, more preferably amorphous carbon, which is a hard carbonfilm. In this case, the release layer 16 (i.e., carbon layer) has acarbon content of preferably 60 atom % or more, more preferably 70 atom% or more, most preferably 80 atom % or more, particularly preferably 85atom % or more, measured by XPS. The release layer has no upper limit ofcarbon content, and the upper limit may be 100 atom %, but realistically98 atom % or less. The release layer 16 (especially carbon layer) maycontain incidental impurities (e.g., oxygen, carbon, and hydrogenderived from the surrounding environment such as atmosphere).Furthermore, metal atoms may be incorporated into the release layer 16(especially carbon layer) during the deposition process of theantireflective layer 17 or the extremely-thin copper layer 18. Lowinterdiffusion and reactivity with carriers of carbon can preventformation of metal bond between the copper foil layer and the bondinginterface caused by high temperature during press processing at atemperature exceeding 300° C., resulting in maintaining ready removal ofcarriers. This release layer 16 is also preferably formed by vapor phasedeposition process such as sputtering in view of a reduction in excessimpurities in the amorphous carbon and the continuous productivity withthe deposition of the interlayer 14. The release layer 16 has athickness of preferably 1 to 20 nm, more preferably 1 to 10 nm. Thisthickness is determined from the cross section of the layer withtransmission electron microscopy-energy dispersive X-ray spectroscopy(TEM-EDX).

The antireflective layer 17 disposed as desired functions to preventreflection of light. Preferably, the antireflective layer 17 is composedof at least one metal selected from the group consisting of Cr, W, Ta,Ti, Ni and Mo, and at least the surface adjacent to the extremely-thincopper layer 18 is composed of an aggregate of metal particles. In thiscase, the antireflective layer 17 may have a layer structure composedentirely of an aggregate of metal particles, or a layer structure of aseveral layers including a layer composed of aggregates of metalparticles and a layer which is non-particulate at the bottom thereof. Asdescribed above, the aggregate of metal particles of the surfaceadjacent to the extremely-thin copper layer 18 of the antireflectivelayer 17 exhibits a desirable dark color due to the metal material andgranular form, and its dark color provides a desirable visual contrastto the wiring layer composed of copper, resulting in the improvedvisibility in image inspection (e.g., automatic optical inspection(AOI)). That is, the surface of the antireflective layer 17 diffuselyreflects light due to the convex shape of the metal particles to bevisually recognized as black. Furthermore, the antireflective layer 17has an adequate adhesion and releasability with respect to the releaselayer 16, excellent adhesion to the extremely-thin copper layer 18, andhigh peeling resistance against the developer at the time of forming thephotoresist layer. The glossiness Gs (60°) of the surface of theantireflective layer 17 adjacent to the extremely-thin copper layer 18is preferably 500 or less in view of such improved contrast andvisibility, more preferably 450 or less, still more preferably 400 orless, particularly preferably 350 or less, and most preferably 300 orless. The lower limit of the glossiness Gs (60°) is preferably as low aspossible, but the surface adjacent to the extremely-thin copper layer 18of the antireflective layer 17 has a glossiness Gs (60°) of effectively100 or more, and more effectively 150 or more. The specular glossinessGs (60°) is determined by image analysis of roughened particles inaccordance with JIS Z 8741-1997 (specular glossiness—measurement method)with a commercially available gloss meter.

In more detail, a copper foil provided with a carrier in which anantireflective layer 17 composed of a predetermined metal, having anaggregate of metal particles at least on the surface adjacent to theextremely-thin copper layer 18, is interposed between the release layer16 and the extremely-thin copper layer 18 has the following advantages:(1) excellent chemical resistance of the antireflective layer againstthe copper flash etching solution during the formation of the wiringlayer on the surface of the coreless support and (2) excellentvisibility of the wiring layer due to high contrast to theantireflective layer in image inspection (e.g., automatic opticalinspection (AOI)) after copper flash etching. Regarding advantage (1),at least one metal selected from Cr, W, Ta, Ti, Ni and Mo constitutingthe antireflective layer 17 cannot be etched away in the copper flashetching solution, and thus exhibits high chemical resistance against thecopper flash etching solution. Regarding advantage (2), the aggregate ofmetal particles constituting at least the surface adjacent to theextremely-thin copper layer 18 of the antireflective layer 17 exhibits adesirable dark color due to the metallic material and granular form, andits dark color provides a desirable visual contrast to the wiring layercomposed of copper, resulting in the improved visibility in imageinspection (e.g., automatic optical inspection (AOI)). In addition, themanufacture of a coreless support provided with a wiring layer or aprinted wiring board using the copper foil provided with a carrier ofthe present invention has further advantage (3): The erosion of thewiring layer exposed under the antireflective layer can be significantlyreduced when the antireflective layer is removed by flash etching. Inother words, a highly selective etching solution may be used in flashetching at least one metal selected from Cr, W, Ta, Ti, Ni and Moconstituting the antireflective layer 17 to reduce or prevent etchingaway of the copper from the wiring layer in the etching solution.

In view of improved contrast and visibility and improved uniformity offlash etching, the surface adjacent to the extremely-thin copper layer18 of the antireflective layer 17 is preferably composed of an aggregateof metal particles having a projected area circle equivalent diameter ofpreferably 10 to 100 nm, more preferably 25 to 100 nm, and mostpreferably 65 to 95 nm, determined by SEM image analysis. Such aprojected area circle equivalent diameter can be determined byphotographing the surface of the antireflective layer 17 with a scanningelectron microscope at a predetermined magnification (e.g., 50,000times) and analyzing the observed SEM image. Specifically, thearithmetic mean value of projected area circle equivalent diametersmeasured using commercially available image analysis particle sizedistribution software is preferably employed.

The antireflective layer 17 is composed of at least one metal selectedfrom Cr, W, Ta, Ti, Ni and Mo, preferably at least one metal selectedfrom Ta, Ti, Ni and Mo, more preferably at least one metal selected fromTi, Ni and Mo, most preferably Ti. These metals may be either puremetals or alloys. In any event, essentially unoxidized metals(essentially not metal oxides) are preferred because they exhibit adesired dark color which improves the visual contrast to Cu.Specifically, the antireflective layer 17 has an oxygen content ofpreferably 0 to 15 atom %, more preferably 0 to 13 atom %, mostpreferably 1 to 10 atom %. In any case, the metal cannot be etched awayin the copper flash etching solution, and thus exhibits high chemicalresistance against the copper flash etching solution. The antireflectivelayer 17 has a thickness of preferably 1 to 500 nm, more preferably 10to 300 nm, most preferably 20 to 200 nm, particularly preferably 30 to150 nm.

The extremely-thin copper layer 18 may be manufactured by any process.Examples of the process include wet processes, such as electrolesscopper plating and electrolytic copper plating; physical vapordeposition, such as sputtering and vacuum vapor deposition; chemicalvapor deposition; and combination thereof. A particularly preferredextremely-thin copper layer is manufactured by vapor phase deposition,for example, sputtering or vacuum vapor deposition because the resultingcopper foil is extremely-thin and is suitable to meet a fine pitch, andthe most preferred is manufactured by sputtering. Although theextremely-thin copper layer is preferably not roughened, the layer maybe preliminarily or secondarily roughened by soft etching, rinsing, oroxidation-reduction with proviso that the wiring pattern can be readilyformed during the production of printed wiring boards. Although theextremely-thin copper layer 18 may have any thickness, the layer has athickness of preferably 50 to 3000 nm, more preferably 70 to 2500 nm,still more preferably 80 to 2000 nm, particularly preferably 90 to 1500nm, most preferably 120 to 1000 nm or 150 to 500 nm to satisfy the finepitch as described above. The extremely-thin copper layer having such athickness within this range is preferably manufactured by sputteringfrom the viewpoint of uniformity of in-plane thickness of layer andproductivity in sheet form or roll form.

The extremely-thin copper layer 18 has a surface remote from the releaselayer 16 (the outer surface of the extremely-thin copper layer 18), andthe surface has an arithmetic average roughness Ra of preferably 1.0 to100 nm, more preferably from 2.0 to 40 nm, still more preferably from3.0 to 35 nm, particularly preferably from 4.0 to 30 nm, most preferablyfrom 5.0 to 15 nm, measured in accordance with JIS B 0601-2001. Such acopper foil 10 provided with a carrier having a smaller arithmeticaverage roughness is suitable for forming an ultrastructural wiringpatter having such a fine line/space (US) of (13 μm or less)/(13 μm orless) (e.g., 12 μm/12 μm to 2 μm/2 μm) in the printed circuit board.

It is preferred that the extremely-thin copper layer 18, the optionalantireflective layer 17, the optional interlayer 14 (e.g., the adhesivemetal layer 14 a and/or the release assisting layer 14 b or theintermediate alloy layer), and the optional release layer 16 (i.e., atleast the extremely-thin copper layer 18, for example, theextremely-thin copper layer 18 and the antireflective layer 17) extendto the end faces of the carrier 12 to cover the end faces of the carrier12. More specifically, it is preferred that not only the surface butalso the end faces of the carrier 12 be covered with at least theextremely-thin copper layer 18. Covering the end faces in addition tothe surface can prevent intrusion of the chemical solution from thecarrier 12 in the printed wiring board process, and also can effectivelyprevent chipping due to peeling at the side ends, i.e., chipping of thecoating on the release layer 16 (i.e., the extremely-thin copper layer18 and the antireflective layer 17, if present,) when the corelesssupport is handled (for example, when the coreless support is carried byrollers). The adhesive metal layer 14 a has a thickness (in thedirection perpendicular to the end face, hereinafter referred to as“end-face thickness”) on the end face of the carrier 12 of preferably 2to 350 nm, more preferably 3 to 220 nm, most preferably 5 to 150 nm,particularly preferably 6 to 70 nm. The release assisting layer 14 b hasan end-face thickness of preferably 2 to 350 nm, more preferably 3 to220 nm, most preferably 5 to 150 nm, particularly preferably 6 to 70 nm.The interlayer 14 as an intermediate alloy layer has an end-facethickness of preferably 2 to 350 nm, more preferably 3 to 220 nm, mostpreferably 5 to 150 nm, particularly preferably 6 to 70 nm. The releaselayer 16 has an end-face thickness of preferably 0 to 15 nm, morepreferably 0 to 3 nm, most preferably 0 to 1 nm, particularly preferably0 to 0.5 nm, most preferably 0 nm. In other words, it is most preferredthat the release layer 16 be not formed on the end faces of the carrier.The antireflective layer 17 has an end-face thickness of preferably 2 to350 nm, more preferably 3 to 220 nm, most preferably 5 to 150 nm,particularly preferably 6 to 70 nm. The extremely-thin copper layer 18has an end-face thickness of preferably 15 to 2800 nm, more preferably20 to 1800 nm, most preferably 25 to 1400 nm, particularly preferably 27to 1350 nm, particularly preferably 35 to 700 nm, most preferably 45 to350 nm. Furthermore, the coating region on the end faces of the carrier12 covers a region of preferably 0.1 mm or more in the thicknessdirection (perpendicular to the carrier surface) from the surface of thecarrier 12, more preferably a region of 0.2 mm or more, more preferablythe entire end face of the carrier 12. In this way, chipping of the filmat the side ends of the coreless support and the penetration of thechemical liquid into the carrier in the printed wiring board process canbe effectively prevented.

Production of Copper Foil Provided with Carrier

It is preferred that the copper foil 10 provided with a carrier of thepresent invention can be manufactured by providing the carrier 12 andforming an interlayer layer 14 (e.g., double-layer structure of anadhesive metal layer 14 a and a release assisting layer 14 b or onelayer structure of an intermediate alloy layer), a release layer 16, anoptional antireflective layer 17 (if present), and a extremely-thincopper layer 18 be formed by vapor phase deposition because they aresuitable for fine pitch requirements due to extremely-thin standards.Examples of the vapor phase deposition include sputtering, vacuum vapordeposition, and ion plating, most preferably sputtering from theviewpoint of controlling the film thickness over a wide range of 0.05 nmto 5,000 nm and maintaining the uniform film thickness over a wide widthor wide area. In particular, forming all of the interlayer 14, therelease layer 16, the antireflective layer 17 (if present), and theextremely-thin copper layer 18 by sputtering remarkably enhances theefficiency of manufacturing. The vapor phase deposition process can becarried out under known conditions with any known vapor depositionsystem. For example, if sputtering is used, then any of various knownsputtering techniques such as magnetron sputtering, bipolar sputteringand counter target sputtering can be used. Magnetron sputtering ispreferred in view of high deposition rate and high productivity.Sputtering can be performed with a direct current (DC) supply or radiofrequency (RF) supply. Regarding the target shape, a well-known platetarget can be used, but it is desirable to use a cylindrical target fromthe viewpoint of the efficiency of use of the target. Vapor phasedeposition of each of the interlayer 14 (e.g., double-layer structure ofan adhesive metal layer 14 a and a release assisting layer 14 b or onelayer structure of an intermediate alloy layer), the release layer 16,the antireflective layer 17 (if present), and the extremely-thin copperlayer 18 (preferably a sputtering) will be described.

It is preferred that vapor phase deposition of the adhesive metal layer14 a be carried out by magnetron sputtering in a non-oxidizingatmosphere with a target composed of at least one metal selected fromthe group consisting of Ti, Cr, and Ni in view of improved uniformity infilm thickness distribution. The silicon target preferably has a purityof 99.9% or more. The gas used for sputtering includes inert gas such asargon gas. Argon can be supplied at any flow rate, which may bedetermined as appropriate according to dimensions of the sputteringchamber and deposition conditions. The pressure during film depositionis preferably set in a range of 0.1 to 20 Pa from the view point ofcontinuous formation of a stable film without operation failures such asabnormal discharge and plasma irradiation failure. This pressure rangecan be set by adjusting the electric power for film deposition and theflow rate of argon depending on the structure and volume of the device,the exhaust capacity of the vacuum pump, and the rated capacity of powersupply for the film deposition. The sputtering power (per unit area ofthe target) can be appropriately determined within the range of 0.05 to10.0 W/cm² from the view point of, for example, the uniform thicknessand productivity of the film.

It is preferred that vapor phase deposition of the release assistinglayer 14 b be carried out by magnetron sputtering with a copper targetunder a non-oxidizing atmosphere in terms of the uniformity in filmthickness distribution. The copper target preferably has a purity of99.9% or more. The gas used for sputtering is preferably inert gas suchas argon gas. Argon can be supplied at any flow rate, which may bedetermined as appropriate according to dimensions of the sputteringchamber and deposition conditions. The pressure during film depositionis preferably set in a range of 0.1 to 20 Pa from the view point ofcontinuous formation of a stable film without operation failures such asabnormal discharge and plasma irradiation failure. This pressure rangecan be set by adjusting the electric power for film deposition and theflow rate of argon depending on the structure and volume of the device,the exhaust capacity of the vacuum pump, and the rated capacity of powersupply for the film deposition. The sputtering power (per unit area ofthe target) can be appropriately determined within the range of 0.05 to10.0 W/cm² from the view point of, for example, the uniform thicknessand productivity of the film.

It is preferred that the interlayer 14 of the intermediate alloy layerbe deposited by magnetron sputtering with an alloy target of Cu with atleast one metal M selected from the group consisting of Ti, Cr, Mo, Mn,W and Ni under a non-oxidizing atmosphere in terms of the uniformity infilm thickness distribution. The copper target preferably has a purityof 99.9% or more. The gas used for sputtering is preferably inert gassuch as argon gas. Argon can be supplied at any flow rate, which may bedetermined as appropriate according to dimensions of the sputteringchamber and deposition conditions. The pressure during film depositionis preferably set in a range of 0.1 to 20 Pa from the view point ofcontinuous formation of a stable film without operation failures such asabnormal discharge and plasma irradiation failure. This pressure rangecan be set by adjusting the electric power for film deposition and theflow rate of argon depending on the structure and volume of the device,the exhaust capacity of the vacuum pump, and the rated capacity of powersupply for the film deposition. The sputtering power (per unit area ofthe target) can be appropriately determined within the range of 0.05 to10.0 W/cm² from the view point of, for example, the uniform thicknessand productivity of the film.

It is preferred that the release layer 16 be deposited by a vapor phasedeposition (preferably sputtering) with a carbon target under an inertatmosphere such as argon. The carbon target is preferably composed ofgraphite, but may contain incidental impurities (e.g., oxygen or carbonfrom the surrounding environment such as atmosphere). The carbon targetpreferably has a purity of 99.99% or more, more preferably 99.999% ormore. Furthermore, the pressure during film deposition is preferably setin a range of 0.1 to 2.0 Pa from the view point of continuous formationof a stable film without operation failures such as abnormal dischargeand plasma irradiation failure. This pressure range can be set byadjusting the electric power for film deposition and the flow rate ofargon depending on the structure and volume of the device, the exhaustcapacity of the vacuum pump, and the rated capacity of power supply forthe film deposition. The sputtering power (per unit area of the target)can be appropriately determined within the range of 0.05 to 10.0 W/cm²from the view point of, for example, the uniform thickness andproductivity of the film.

It is preferred that the antireflective layer 17 be deposited bymagnetron sputtering with a metal target composed of at least one metalselected from the group consisting of Cr, W, Ta, Ti, Ni, and Mo. Thetarget has preferably a purity of 99.9% or more. In particular, theantireflective layer 17 is preferably formed by a magnetron sputteringin an inert gas atmosphere such as argon at a pressure of 1 to 20 Pa.The sputtering pressure is more preferably 2 to 18 Pa, still morepreferably 3 to 15 Pa. Such a sputtering pressure is remarkably higherthan conventional sputtering pressures, so that an aggregate of metalparticles can be formed in a desired form uniformly in the in-planesurface without essentially oxidizing the surface of the antireflectivelayer 17. The above sputtering conditions can provide a desiredprojected area circle equivalent diameter and a desired glossiness Gs(60°) and can also advantageously provide continuous formation of astable film without operation failures such as abnormal discharge andplasma irradiation failure. The pressure range may be controlled byadjusting the electric power for film deposition and the flow rate ofthe argon gas depending on the structure and volume of the device, theexhaust capacity of the vacuum pump, and the rated capacity of powersupply for the film deposition. Argon can be supplied at any flow rate,which may be determined as appropriate according to dimensions of thesputtering chamber and deposition conditions. The sputtering power (perunit area of the target) can be appropriately determined within therange of 1.0 to 15.0 W/cm² from the view point of, for example, theuniform thickness and productivity of the film. Furthermore, it ispreferred that the carrier temperature be kept constant during filmformation in view of ease of achieving stable film characteristics (forexample, film resistance and crystal size). The carrier temperatureduring film formation is preferably adjusted within the range of 25 to300° C., more preferably 40 to 200° C., and furthermore preferably 50 to150° C.

The extremely-thin copper layer 18 is preferably formed by vapor phasedeposition (preferably sputtering process) under an inert atmospheresuch as argon with a copper target. The copper target is preferablycomposed of metallic copper, but may contain incidental impurities. Thecarbon target preferably has a purity of 99.9% or more, more preferably99.99% or more, still more preferably 99.999%. A cooling mechanism forthe stage may be provided at the time of sputtering to avoid atemperature rise during the vapor phase deposition of the extremely-thincopper layer 18. The pressure during film deposition is preferably setin a range of 0.1 to 2.0 Pa from the view point of continuous formationof a stable film without operation failures such as abnormal dischargeand plasma irradiation failure. This pressure range can be set byadjusting the electric power for film deposition and the flow rate ofargon depending on the structure and volume of the device, the exhaustcapacity of the vacuum pump, and the rated capacity of power supply forthe film deposition. The sputtering power (per unit area of the target)can be appropriately determined within the range of 0.05 to 10.0 W/cm²from the view point of, for example, the uniform thickness andproductivity of the film.

The interlayer 14, the release layer 16, the antireflective layer 17and/or the extremely-thin copper layer 18 on the end faces of thecarrier 12 can be readily formed by deposition while the end face of thecarrier 12 is being exposed on the stage in the sputtering process. Inthis case, the end face of the carrier 12 is typically formed into athickness (end-face thickness) of 20% to 70% of the thickness of thelayer deposited on the surface of the carrier 12. In the meantime, inthe case of forming an extremely-thin film on the end face, such asforming the release layer 16, it is preferred to sputter with the sideends of the carrier 12 shielded. Examples of this type of shieldinginclude shielding by a masking tape and shielding by a masking plate.

Laminate for Coreless Support

The copper foil provided with a carrier of the present invention may beprovided in the form of a laminate for a coreless support. In otherwords, a preferred embodiment of the present invention provides alaminate for a coreless support comprising the copper foil provided witha carrier. The laminate for a coreless support has the following twoforms: (i) The first form of the laminate for a coreless support is inthe form of the copper foil 10 provided with a carrier itself. Indetail, the interlayer 14, the release layer 16, the optionalantireflective layer 17, and the extremely-thin copper layer 18 areformed in this order on at least one surface of the carrier 12; or theinterlayer 14, the release layer 16, the optional antireflective layer17, the extremely-thin copper layer 18 are formed in this order on eachsurface of the carrier. In any case, this form can be achieved if thecarrier 12 itself is rigid such as a glass plate or a metal plate andcan function as a support. For example, a glass carrier 12, which islightweight, has a low thermal expansion coefficient, is rigid and has aflat surface, has an advantage in that the surface of the extremely-thincopper layer 18 can be extremely smooth. (ii) The second form of thelaminate for a coreless support may be provided in a form having anadhesive layer on the outer surface of the carrier 12 (the outer surfaceof the carrier 12 being remote from the release layer 16). This form isavailable in the case where the carrier 12 is composed of a nonrigidmaterial such as a metal foil or a resin film. In this case, examples ofthe adhesive layer include a resin layer and a fiber reinforced prepreg(such as glass). For example, a possible layer configuration consists ofan extremely-thin copper layer 18, an optional antireflective layer 17,a release layer 16, an interlayer 14, a carrier 12, an adhesive layer(not shown), a carrier 12, an interlayer 14, a release layer 16, anoptional antireflective layer 17, and an extremely-thin copper layer 18.The interlayer 14 may has a double layer structure of an adhesive metallayer 14 a and a release assisting layer 14 b in this order from thecarrier 12 side, or may be a single intermediate alloy layer asdescribed above.

Production of Coreless Support Provided with Wiring Layer

A coreless support provided with a wiring layer can be manufacturedusing a copper foil provided with a carrier of the present invention.Hereinafter, a preferred method of manufacturing a coreless supportprovided with a wiring layer will be described. The method ofmanufacturing a coreless support provided with a wiring layer includessteps of: (1) preparing a copper foil provided with a carrier, (2)forming a photoresist layer, (3) forming an electrolytic copper platinglayer, (4) peeling off the photoresist layer, and (5) flash etching. Theproduction of a coreless support provided with a wiring layer includingthese steps is schematically shown in FIGS. 3 and 4.

(1) Preparation of Copper Foil Provided with Carrier.

A support for the copper foil 10 provided with a carrier is provided(see FIG. 3 (a)). As described above, the copper foil 10 provided with acarrier can be provided in the form of a laminate for a corelesssupport. In other words, as described above, the copper foil providedwith a carrier may be provided in a form of a carrier foil itself, ormay be provided in a form having an adhesive layer on the outer surfaceof the carrier 12 (the outer surface of the carrier 12 being remote fromthe release layer 16), for example, in a form of a layer structureconsisting of an extremely-thin copper layer 18, an optionalantireflective layer 17, a release layer 16, an interlayer 14, a carrier12, an adhesive layer (not shown), a carrier 12, an interlayer 14, arelease layer 16, an optional antireflective layer 17, and anextremely-thin copper layer 18. The interlayer 14 may has a double layerstructure consisting of an adhesive metal layer 14 a and a releaseassisting layer 14 b in order from the carrier 12 side as shown in FIGS.3 and 4, or may has a single layer structure consisting of anintermediate alloy layer shown in FIG. 1.

(2) Formation of Photoresist Layer

A photoresist layer 20 is formed in a predetermined pattern on thesurface of the extremely-thin copper layer 18 (see FIG. 3 (b)). Thephotoresist is preferably a photosensitive film, for example, aphotosensitive dry film. The photoresist layer 20 may be provided with apredetermined wiring pattern by exposure and development. In this case,the copper foil 10 provide with a carrier of the present invention,which has the interlayer 14, can exhibit high peeling resistance againsta developer (for example, aqueous sodium carbonate solution).

(3) Formation of Electrolytic Copper Plating Layer

An electrolytic copper plating layer 22 is formed on the exposed surfaceof the extremely-thin copper layer 18 (i.e., the portion not masked withthe photoresist layer 20) (see FIG. 3(c)). The electrolytic copperplating can be carried out by any known process without any limitation.

(4) Peeling-Off of Photoresist Layer

The photoresist layer 20 is then peeled off. As shown in FIG. 4 (d), theelectrolytic copper plating layer 22 remains in the form of a wiringpattern, and the portions of extremely-thin copper layer 18 where thewiring pattern is not formed are exposed.

(5) Copper Flash Etching

Unnecessary portions of the extremely-thin copper layer 18 are removedby copper flash etching to prepare a coreless support (hereinafterreferred to as a coreless support 26 provided with a wiring layer) onwhich the wiring layer 24 is formed. In the case where the copper foil10 with a carrier has the antireflective layer 17, the unnecessaryportions of the extremely-thin copper layer 18 are removed by copperflash etching to leave the antireflective layer 17 exposed (that is, thecopper flash etching is stopped on the antireflective layer 17). It ispreferred that the flashing liquid contain at least one of a mixture ofsulfuric acid and hydrogen peroxide, sodium persulfate and potassiumpersulfate because the exposed extremely-thin copper layer 18 can bereliably etched while excess etching of the electrolytic copper platinglayer 22 is prevented. Thus, as shown in FIG. 4(e), the electrolyticcopper plating layer 22 and the extremely-thin copper layer 18 remain inthe form of a wiring pattern, while portions of the antireflective layer17 where the wiring pattern is not formed are not eluted by the flashetching solution to be exposed on the surface. At least one metalselected from Cr, W, Ta, Ti, Ni, and Mo constituting the antireflectivelayer 17 cannot be eluted in the copper flash etching solution, and thusexhibits high chemical resistance against the copper flash etchingsolution. In other words, the antireflective layer 17 is not removedduring copper flash etching but is left in the exposed state for thenext image inspection process.

(6) Image Inspection and Other Steps (Optional Process)

After the copper flash etching, it is preferred that the image of thecoreless support 26 provided with a wiring layer (specifically, thewiring layer 24) be inspected. Typically, the image is inspected asfollows: a binary image of a wiring pattern is acquired with anautomatic optical inspection (AOI) system by irradiating the supportwith predetermined light from a light source. Pattern matching betweenthe binary image and the design data image is then carried out toevaluate match or mismatch between these images. It is preferred thatthe image inspection be performed while the antireflective layer 17 (ifpresent) remains exposed. The aggregate of metal particles constitutingat least the surface of the antireflective layer 17 exhibits a desirabledark color due to the metallic material and granular form, leading to adesirable visual contrast to the wiring layer 24 composed of copper,resulting in improved visibility in image inspection (e.g., automaticoptical inspection (AOI)).

After the above image inspection, it is preferred to mount an electronicelement 28, such as a chip, on the coreless support 26 provided withwiring layer, if necessary. A printed wiring board can thereby bemanufactured. As described above, such a process of mounting the chipafter forming the wiring layer 24 is called RDL-first process. Thismethod enables image inspection of the wiring layer on the surface ofthe coreless support and each build-up wiring layer stacked thereafter,prior to chip mounting, so that the chip may be mounted only on thenon-defective portion of each wiring layer. As a result, the RDL-firstmethod, which can avoid wasteful use of the chips, is economicallyadvantageous compared to the Chip-first method, which sequentiallystacks the wiring layer on the surface of the chip. In the case wherethe copper foil 10 with a carrier of the present invention has theantireflective layer 17, there is provided sufficient contrast betweenthe surface of the electrolytic copper plating layer 22 and the surfaceof the antireflective layer 17 in image inspection, resulting inhigh-accuracy image inspection. Accordingly, for example, the binaryimages of the wiring pattern acquired by the automatic opticalinspection (AOI) system are more accurate and clear. Thus, in theprocess of manufacturing a printed wiring board (in particular, theRDL-first process), images on a wiring layer before chip mounting can beinspected with high accuracy, resulting in improved product yield.Examples of the optional electronic element 28 mounted on the wiringlayer of the coreless support 26 include a semiconductor element, a chipcapacitor, and a resistor. Examples of a method of mounting electronicelements include a flip chip mounting method and a die bonding method.The flip chip mounting method involves bonding the mounting pad of theelectronic elements 28 to the wiring layer 24 on the coreless support26. Columnar electrodes (pillars) and solder bumps a may be formed onthis mounting pad. A sealing resin film such as non-conductive film(NCF) may be attached to the surface of the wiring layer 24 of thecoreless support 26 before mounting. Although the bonding is preferablyperformed using a low melting point metal such as solder, an anisotropicconductive film may be used. In the die bonding method, the surfaceopposite to the mounting pad surface of the electronic element 28 isbonded to the wiring layer 24 on the surface of the coreless support 26.For this bonding, it is preferred to use a paste or a film composed of aresin composition containing a thermosetting resin and a thermallyconductive inorganic filler.

Production of Printed Wiring Board

The printed wiring board can be manufactured using the coreless supportprovided with the wiring layer of the present invention. Hereinafter, apreferred manufacturing method of the printed wiring board will bedescribed. The method of manufacturing this printed wiring boardinvolves the steps of (1) manufacturing a coreless support provided witha wiring layer, (2) preparing a laminate with a build-up layer, (3)separating the laminate with a build-up layer, and (4) processing amultilayer wiring board. The method of manufacturing a printed wiringboard including these steps is schematically shown in FIGS. 3 to 5 (inparticular, FIG. 5).

(1) Step of Manufacturing Coreless Support Provided with Wiring Layer

The coreless support 26 provided with wiring layer is manufactured bythe method of the present invention described above. In other worlds,the production of the printed wiring board of the present inventionincludes a series of steps of the above-described method ofmanufacturing a coreless support provided with a wiring layer, and therepetitive description thereof will be omitted.

(2) Step of Preparing Laminate with Build-Up Layer

The build-up layer 30 is formed on the surface of the coreless support26 provided with wiring layer on which the wiring layer 24 is formed toprepare a laminate 32 with a build-up layer (see FIG. 5(g)). Althoughdetails of the build-up layer 30 are not shown in FIG. 5, any knownbuild-up wiring layer structure commonly used in printed wiring boardsmay be adopted.

(3) Step of Separating Laminate with Build-Up Layer

The multilayer wiring board 34 including the build-up layer 30 isprepared by separating the laminate 32 with build-up layer with therelease layer 16. That is, the carrier 12, the interlayer 14, and therelease layer 16 are peeled off. The separation step such as physicalseparation and chemical separation can be employed in the separationstep. Physical separation is preferred. The physical separation involvesseparating the carrier 12 from the build-up layer 30 into the multilayerwiring board 34 (see FIG. 5(h)) by hand, or with a tool or a machine. Inthis case, the copper foil 10 with a carrier of the present inventionhas an interlayer 14, which leads to high stability of mechanical peelstrength of the carrier 12. As a result, the carrier 12 can be readilypeeled off together with the interlayer 14 and the peeling layer 16.

(4) Step of Processing Multilayer Wiring Board

The multilayer wiring board 34 is processed to prepare a printed wiringboard 36 (FIG. 5 (i)). In the case where the antireflective layer 17 ispresent in the multilayer wiring board 34, it is preferred that theantireflective layer 17 be removed by flash etching. The appropriateetching solution for the flash etching is preferably selected accordingto the metal constituting the antireflective layer 17, for example, asexemplified in the Table 1 below. Representative etching solutions areexemplified in Table 1, but the present invention is not limitedthereto, and the conditions such as the type and concentration of acidand ammonium salt, and temperature can be appropriately varied from theconditions shown in Table 1.

TABLE 1 Constituent element of Desirable antireflective Desirablecomponents contained in etching etching layer solution temperature CrHNO₃ (5%) and cerium(IV) ammonium 40° C. hexanitrate (CAN)(20%) W H₂O₂(30%), triammonium citrate (5%) and 30° C. NH₃ (0.1%) Ta NaOH (30%) 70to 80° C. Ti H₂O₂ (30%), triammonium citrate (5%) and 30° C. NH₃ (0.1%)Ni HNO₃ (20%) and H₂O₂ (10%) 40° C. Mo H₃PO₄, HNO₃ and CH₃COOH 23° C.

The antireflective layer 17 can be selectively flash-etched with such anetching solution, so that erosion of the wiring layer 24 (which iscomposed of copper) exposed under the antireflective layer 17 can besignificantly prevented. In other words, a highly selective etchingsolution may be used in flash etching of at least one metal selectedfrom Cr, W, Ta, Ti, Ni and Mo constituting the antireflective layer 17to reduce or prevent etching away of the copper from the wiring layer 24in the etching solution.

The outer layer of the printed wiring board 36 as shown in FIG. 5 can beprocessed by various methods. For example, an insulating layer and awiring layer as build-up wiring layers may be stacked on the wiringlayer 24 of the printed wiring board 36 as any number of layers, or asolder resist layer may be formed on the surface of the wiring layer 24to perform surface treatment as an outer layer pad such as Ni—Au platingor OSP treatment (water soluble preflux treatment, Organic SolderabilityPreservative). Furthermore, a columnar pillar and other features may beprovided on the outer layer pad. In any case, in general, any knownmethod employed in a printed wiring board can be additionally carriedout.

EXAMPLES

The present invention will be described in further detail by way of thefollowing examples.

Example 1

(1) Preparation of Copper Foil Provided with Carrier

As shown in FIG. 1, an adhesive metal layer 14 a, release assistinglayer 14 b, a release layer 16, and an extremely-thin copper layer 18were deposited in this order on a glass sheet carrier 12 to prepare acopper foil 10 provided with a carrier. The detailed procedures are asfollows. The arithmetic average roughness Ra in the following examplesis measured with a non-contact profilometer (NewView 5032 manufacturedby Zygo Corporation) in accordance with JIS B 0601-2001.

(1a) Provision of Carrier

A glass sheet (material: non-alkali glass, product name: OA 10,manufactured by Nippon Electric Glass Co., Ltd.) having a thickness of700 μm and a surface with an arithmetic average roughness Ra of 0.5 nmwas provided.

The end faces of the carrier 12 were masked with a stainless steelplate, and various layers were formed by sputtering as described below.

(1b) Formation of Adhesive Metal Layer

A titanium adhesive metal layer 14 a having a thickness of 100 nm wasdeposited on the surface of the carrier 12 by sputtering under thefollowing conditions:

-   -   Apparatus: single-wafer type magnetron sputtering system        (manufactured by Tokki Corporation)    -   Target: Ti target (purity: 99.999%) with a diameter of 8 inches        (203.2 mm)    -   Ultimate vacuum Pu: less than 1×10⁻⁴ Pa    -   Carrier gas: Ar (flow rate: 100 sccm)    -   Sputtering pressure: 0.35 Pa    -   Sputtering power: 2,000 W (6.2 W/cm²)    -   Temperature during deposition: 40° C.

(1c) Formation of Release Assisting Layer

A copper release assisting layer 14 b having a thickness of 100 nm wasdeposited on the adhesive metal layer 14 a by sputtering under thefollowing conditions:

-   -   Apparatus: single wafer type DC sputtering system (MLS 464        manufactured by Canon Tokki Corporation)    -   Target: Cu target (purity: 99.98%) with a diameter of 8 inches        (203.2 mm)    -   Ultimate vacuum Pu: less than 1×10⁻⁴ Pa    -   Carrier gas: Ar (flow rate: 100 sccm)    -   Sputtering pressure: 0.35 Pa    -   Sputtering power: 2,000 W (6.2 W/cm²)    -   Temperature during deposition: 40° C.

(1d) Formation of Release Layer

An amorphous carbon layer having a thickness of 3 nm as a release layer16 was deposited on the release assisting layer 14 b by sputtering underthe following conditions:

-   -   Apparatus: single wafer type DC sputtering system (MLS 464        manufactured by Canon Tokki Corporation)    -   Target: carbon target (purity: 99.999%) with a diameter of 8        inches (203.2 mm)    -   Ultimate vacuum Pu: less than 1×10⁻⁴ Pa    -   Carrier gas: Ar (flow rate: 100 sccm)    -   Sputtering pressure: 0.35 Pa    -   Sputtering power: 100 W (0.3 W/cm²)    -   Temperature during deposition: 40° C.

(1e) Formation of Antireflective Layer

A nickel antireflective layer 17 having a thickness of 100 nm wasdeposited on the surface of the release layer 16 by sputtering under thefollowing conditions:

-   -   Apparatus: single wafer type DC sputtering system (MLS 464        manufactured by Canon Tokki Corporation)    -   Target: Ti target (purity: 99.999%) with a diameter of 8 inches        (203.2 mm)    -   Carrier gas: Ar (flow rate: 100 sccm)    -   Ultimate vacuum Pu: less than 1×10⁻⁴ Pa    -   Sputtering pressure: 12 Pa    -   Sputtering power: 2,000 W (6.2 W/cm²)

(1f) Formation of Extremely-Thin Copper Layer

An extremely-thin copper layer 18 having a thickness of 300 nm wasdeposited on the antireflective layer 17 under the following conditions.The surface remote from the release layer 16 (i.e., the outer surface)of the resulting extremely-thin copper layer 18 had an arithmeticaverage roughness Ra of 3 nm.

-   -   Apparatus: single wafer type DC sputtering system (MLS 464        manufactured by Canon Tokki Corporation)    -   Target: Cu target (purity: 99.98%) with a diameter of 8 inches        (203.2 mm)    -   Ultimate vacuum Pu: less than 1×10−4 Pa    -   Carrier gas: Ar (flow rate: 100 sccm)    -   Sputtering pressure: 0.35 Pa    -   Sputtering power: 2,000 W (6.2 W/cm²)    -   Temperature during deposition: 40° C.

(1g) Components Analysis

The samples for, for example, components analysis are prepared under thesame conditions as those of manufacturing the adhesive metal layer 14 a,release assisting layer 14 b, release layer 16, and antireflective layer17 of the resulting copper foil provided with carrier: that is, a firstsample provided with only an adhesive metal layer 14 a on a glass sheet,a second sample provided with only a release assisting layer 14 b on aglass sheet, a third sample provided with only a release layer 16 on aglass sheet, and a fourth sample provided with only an antireflectivelayer 17 on a glass sheet were separately prepared. Components of eachsample were analyzed as follows to determine the components of eachlayer.

<Components Analyses of Adhesive Metal Layer, Release Assisting Layer,and Antireflective Layer>

Monitoring samples for surface analysis were prepared for the adhesivemetal layer 14 a, the release assisting layer 14 b, and theantireflective layer 17 to perform elemental analysis by time-of-flightsecondary ion mass spectrometry (TOF-SIMS). This measurement was carriedout in a constant current mode under the condition of 800 V and 3 mA.The results of the compositions of the adhesive metal layer 14 a, therelease assisting layer 14 b and the antireflective layer 17 were asfollows.

Adhesive metal layer 14 a: 92.5 atom % Ti, 7.5 atom % O

Release assisting layer 14 b: 99 atom % Cu, 1 atom % O

Anti-reflective layer 17: 99.6 atom % Ti, 0.4 atom % O

<Components Analysis of Release Layer>

Elemental analysis was performed on the release layer 16 (i.e., thecarbon layer) by XPS to determine the carbon content. The release layer16 had a carbon content of 93 atom % (C+O=100%).

<Measurement of Projected Area Circle Equivalent Diameter ofAntireflective Layer Surface>

The sample immediately after the formation of the antireflective layer17 was taken out, and the surface of the antireflective layer 17 wasphotographed at a magnification of 50,000 with a scanning electronmicroscope to acquire an SEM image. The projected area circle equivalentdiameters were measured by analysis of the binary image from theacquired SEM image. The image analysis was performed with image analysistype particle size distribution software (Mac-VIEW, manufactured byMountech Co., Ltd.). For arbitrary 50 or more particles, the projectedarea circle equivalent diameter was measured for individual particles tocalculate the arithmetic mean value thereof. The resulting projectedarea circle equivalent diameter of the surface of the antireflectivelayer 17 was 60 nm.

Example 2

A copper foil provided with a carrier was prepared and evaluated as inExample 1 except that a nickel sputtering target (purity: 99.999%) wasused to form a nickel layer instead of a titanium layer as the adhesivemetal layer 14 a. The results are shown in Table 2. The arithmeticaverage roughness Ra of the surface remote from the release layer 16 ofthe extremely-thin copper layer 18 was 3.7 nm. The composition of eachlayer other than the adhesive metal layer 14 a was substantially thesame as that in Example 1. The adhesive metal layer 14 a has acomposition of 99.5 atom % Ni and 0.5 atom % O.

Example 3

A copper foil provided with a carrier was prepared and evaluated as inExample 1 except that a chromium sputtering target (purity: 99.999%) wasused to form a chromium layer instead of a titanium layer as theadhesive metal layer 14 a. The results are shown in Table 2. Thearithmetic average roughness Ra of the surface remote from the releaselayer 16 of the extremely-thin copper layer 18 was 3.5 nm. Thecomposition of each layer other than the adhesive metal layer 14 a wassubstantially the same as that in Example 1. The adhesive metal layer 14a has a composition of 98.0 atom % Cr and 2.0 atom % O.

Example 4

A copper foil provided with a carrier was prepared and evaluated as inExample 1 except that a carrier 12 of an alumina plate (product name:A-476, manufactured by Kyocera Corporation) having a surface with anarithmetic average roughness Ra of 0.2 μm and a thickness of 1000 μm wasprepared, so that the surface was treated by chemical mechanicalpolishing (CMP) into the surface with an arithmetic average roughness Raof 1.0 nm. The results are shown in Table 2. The arithmetic averageroughness Ra of the surface remote from the release layer 16 of theextremely-thin copper layer 18 was 2.1 nm. The composition of each layerwas substantially the same as that in Example 1.

Example 5

A copper foil provided with a carrier was prepared and evaluated as inExample 1 except that a carrier 12 of an yttria-stabilized zirconiaplate (yttrium oxide 10 wt %) having a surface with an arithmeticaverage roughness Ra of 1.0 nm and having a thickness of 500 μm(manufactured by Shinkosha Co., Ltd.) was prepared. The results areshown in Table 2. The arithmetic average roughness Ra of the surfaceremote from the release layer 16 of the extremely-thin copper layer 18was 2.2 nm. The composition of each layer was substantially the same asthat in Example 1.

Example 6 (Comparative)

A copper foil provided with a carrier was prepared and evaluated as inExample 1 except that the adhesive metal layer 14 a and the releaseassisting layer 14 b were not formed. The results are shown in Table 2.The arithmetic average roughness Ra of the surface remote from therelease layer 16 of the extremely-thin copper layer 18 was 1.0 nm. Thecomposition of each layer was substantially the same as that in Example1.

Example 7 (Comparative)

A copper foil provided with a carrier was prepared and evaluated as inExample 1 except that an aluminum sputtering target (purity: 99.999%)was used to form an aluminum layer instead of a titanium layer as theadhesive metal layer 14 a. The results are shown in Table 2. Thearithmetic average roughness Ra of the surface remote from the releaselayer 16 of the extremely-thin copper layer 18 was 4.0 nm. Thecomposition of each layer other than the adhesive metal layer 14 a wassubstantially the same as that in Example 1. The adhesive metal layer 14a has a composition of 98 atom % Al and 2 atom % O.

Example 8 (Comparative)

A copper foil provided with a carrier was prepared and evaluated as inExample 1 except that the release assisting layer 14 b was not formed.The results are shown in Table 2. The arithmetic average roughness Ra ofthe surface remote from the release layer 16 of the extremely-thincopper layer 18 was 2.2 nm. The composition of each layer wassubstantially the same as that in Example 1

Example 9 (Comparative)

A copper foil provided with a carrier was prepared and evaluated as inExample 1 except that the release assisting layer 14 a was not formed.The results are shown in Table 2. The arithmetic average roughness Ra ofthe surface remote from the release layer 16 of the extremely-thincopper layer 18 was 3.1 nm. The composition of each layer wassubstantially the same as that in Example 1

Example 10 (Comparative)

A copper foil provided with a carrier was prepared and evaluated as inExample 1 except that a nickel sputtering target (purity: 99.999%) wasused to form a nickel layer instead of a copper layer as the releaseassisting layer 14 b. The results are shown in Table 2. The arithmeticaverage roughness Ra of the surface remote from the release layer 16 ofthe extremely-thin copper layer 18 was 2.5 nm. The composition of eachlayer other than the release assisting layer 14 b was substantially thesame as that in Example 1. The release assisting layer 14 b has acomposition of 99.0 atom % Ni and 1.0 atom % O.

Example 11 to 13

Copper foils provided with carriers were prepared and evaluated as inExample 1 except that a molybdenum layer (Example 11), a tungsten layer(Example 12) and a manganese layer (Example 13) were formed bysputtering in place of the titanium layer as the adhesive metal layer 14a. The results are shown in Table 2.

Examples 14 to 24 (Examples 18 and 19 are Comparative)

Copper foils provided with carriers were prepared and evaluated as inExample 1 except that intermediate alloy layers having the compositionsshown in Table 3 were formed as a single layer structure consisting ofthe interlayer 14 instead of the two-layer structure consisting of theadhesive metal layer 14 a and the release assisting layer 14 b. Theresults are shown in Table 3.

Examples 25 to 29

Copper foils provided with carriers were prepared and evaluated as inExample 1 except that i) an adhesive metal layer 14 a, an releaseassisting layer 14 b, an antireflective layer 17, and an extremely-thincopper layer 18 were formed without masking the end face of the carrier12, and ii) a release layer 16 with a variable thickness (end facethickness) was formed using a stainless steel plate for masking. As aresult, the thickness (end face thickness) of each layer at the end faceof the carrier 12 was as shown below.

-   -   Adhesive metal layer 14 a: titanium layer (end surface        thickness: 35 nm)    -   Release assisting layer 14 b: copper layer (end face thickness:        35 nm)    -   Release layer 16: Carbon layer (various end face thicknesses        shown in Table 4)    -   Antireflective layer 17: titanium layer (end face thickness: 38        nm)    -   Extremely-thin copper layer 18: copper layer (end face        thickness: 100 nm)

Example 30

A copper foil provided with a carrier was prepared and evaluated as inExample 1 except that i) an interlayer 14 as an intermediate alloylayer, a antireflective layer 17, and an extremely-thin copper layer 18were formed without masking the end face of the carrier 12, and ii) arelease layer 16 with a thickness (end face thickness) described belowwas formed using a stainless steel plate for masking.

-   -   Interlayer 13 (intermediate alloy layer): Cu—Mn alloy layer        (elemental ratio Cu:Mn=95:5, end surface thickness: 35 nm)    -   Release layer 16: carbon layer (end face thickness: 0 nm)    -   Antireflective layer 17: titanium layer (end face thickness: 38        nm)    -   Extremely-thin copper layer 18: copper layer (end face        thickness: 100 nm)

Evaluations on Various Items

The copper foil provided with a carrier of each of Examples 1 to 30 wassubjected to evaluation on the following items. The results are shown inTables 2 to 4.

<Evaluation 1: Peeling Resistance of Extremely-Thin Copper Layer AgainstDeveloper>

The surface of the extremely-thin copper layer of each copper foilprovided with a carrier was treated with dilute sulfuric acid of 0.05mol/L to remove the oxide film on the surface, followed by washing withwater and drying. Then, a photosensitive dry film was attached to thesurface of the extremely-thin copper layer, and exposed and developedsuch that a pattern of line/space (L/S)=5 μm/5 μm is given. Developmentwas carried out by showering at 25° C. for 2 min using an aqueous 1.0 wt% sodium carbonate developer. The presence of peeling (or degree ofseparation) of the extremely-thin copper layer due to infiltration ofthe developer into the interface between the extremely-thin copper layerand the carrier (especially between the release layer and the adhesivemetal layer) after the development was evaluated.

The results were rated based on the following criteria.

Rank AA: No peeling of the extremely-thin copper layer was observed.

Rank A: Peeling with a size of 3 μm or less in diameter was observed.

Rank B: Peeling with a size of 50 μm or less in diameter was observed.

Rank C: Peeling with a size larger than 50 μm in diameter was observed.

<Evaluation 2: Peelability Between Carrier and Extremely-Thin CopperLayer>

The peel strength of the copper foil provided with a carrier wasmeasured after a thermal history of solder reflow and vacuum heat press.After panel electrolytic copper plating having a thickness of 18 μm onthe side adjacent the extremely-thin copper layer 18 of the copper foil10 provided with a carrier, the sample was heat-treated by solder reflow(kept at 260° C. or higher for 2 min) (thermal history 1), assumingmount of electronic components, and the copper foil was spontaneouslycooled to room temperature. Thereafter, the copper foil was pressed at atemperature of 220° C. for 90 min under a pressure of 30 kgf/cm²(thermal history 2). The peel strength (gf/cm) of the resultingcopper-clad laminate was measured by peeling off the electrolytic copperplating layer integrated with the extremely-thin copper layer 18(measuring area: 50 mm×20 mm) in accordance with JIS C 6481-1996. Theresulting peel strength (average value) was rated based on the followingcriteria.

Rank A: peel strength of 2 to 10 gf/cm

Rank B: peel strength of 1 to 30 gf/cm (except for 2 to 10 gf/cm)

Rank C: peel strength of less than 1 gf/cm or greater than 30 gf/cm

<Evaluation 3: Evaluation of Film Chipping at Side Ends of CorelessSupport>

Electrolytic copper plating was applied to the coreless support used inEvaluation 1, followed by flash etching of the resultant extremely-thincopper layer with a sulfuric acid-hydrogen peroxide solution to form acoreless support with a wiring pattern. The maximum width (mm) ofchipping of the film (i.e., extremely-thin copper layer andantireflective layer) on the release layer at the side ends of eachcoreless support provided with a wiring pattern was measured to be ratedbased on the following criteria. The results are shown in Tables 2 to 4.

-   -   Rank AA: Less than 0.1 mm (best)    -   Rank A: 0.1 mm or more and less than 1 mm (good)    -   Rank B: 1 mm or more and less than 2 mm (acceptable)    -   Rank C: 2 mm or more (unacceptable)

<Evaluation 4: Evaluation of Fine Pattern Formability of Embedded WiringLayer>

A prepreg and a copper foil were laminated in this order on the corelesssupport provided with the wiring pattern prepared in Evaluation 3 andcured into a laminate with a build-up layer. The laminate with abuild-up layer was mechanically separated at the release layer toprepare a multilayer wiring board including the build-up layer. Theantireflective layer was subjected to flash etching under the conditionsshown in Table 1, and the properties of the wiring layer embedded in thebuild-up layer were observed to be ranked based on the followingcriteria. The results are shown in Tables 2 and 3. One piece was definedas 8 mm×8 mm square and the number of observation pieces in each examplewas set to 336 to count the number of defective pieces in the embeddedwiring. The defective mode includes, for example, shortcutting due topeeling of the extremely-thin copper layer and peelings of the adhesivemetal layer and the release assisting layer, which leave metal adjacentto the carrier when the coreless support is peeled.

-   -   Rank AA: percent defective is less than 5% by number (best)    -   Rank A: percent defective is 5% or more and less than 10% by        number (good)    -   Rank B: percent defective rate is 10% or more and 20% or less by        number (acceptable)    -   Rank C: percent defective is 20% or more and less than 50% by        number (unacceptable)

<Evaluation 5: Evaluation of Chemical Penetration Depth>

A prepreg having a size of 100 mm×100 mm (FR-4 manufactured by PanasonicCorporation, 200 μm thick) was laminated on the coreless support with awiring pattern prepared in Evaluation 3 to cure the prepreg into aprinted wiring board. The printed wiring board was subjected to desmeartreatment using a sodium permanganate solution, and the chemicalpenetration depth (mm) was measured as an indication of the penetratedamount of chemical solution.

This desmear treatment was carried out by the following procedures usingthe process solution shown below (manufactured by Rohm and HaasElectronic Materials LLC).

[Swelling Process]

-   -   Process solution: Circuposit MLB Conditioner 211 (120 mL/L) and        -   Circuposit Z (100 mL/L)    -   Process conditions: immersion for 5 min at 75° C.

[Permanganic Acid Process]

-   -   Process solution: Circuposit MLB promoter 213A (110 mL/L) and        -   Circuposit MLB promoter 213 B (150 mL/L)    -   Process conditions: immersion for 5 min at 80° C.

[Neutralization Process]

-   -   Process solution: Circuposit MLB Neutralizer 216-2 (200 mL/L)    -   Process conditions: immersion for 5 min at 45° C.

The measured chemical penetration depth (mm) was rated based on thefollowing criteria. The results are shown in Tables 2 to 4.

-   -   Rank AA: less than 0.1 mm (best)    -   Rank A: 0.1 mm or more and less than 0.5 mm (good)    -   Rank B: 0.5 mm or more and less than 2 mm (acceptable)    -   Rank C: 2 mm or more (unacceptable)

TABLE 2 Chipping width Percent Peeling of defective resistanceReleasability extremely-thin in pattern Interlayer of extremely-thin ofcarrier copper layer Chemical formation of Adhesive Release copper layerPeel and other layers penetration embedded metal assisting againstdeveloper strength at side ends depth wiring layer Carrier layer layer(μm) (gf/cm) Rank (mm) (mm) (% by number) Ex. 1 Glass Ti Cu  0(AA) 5.1 A1.0(B)  0(AA)  0(AA) Ex. 2 Glass Ni Cu  2(A) 3.5 A 1.3(B) 1.0(B)  9(A)Ex. 3 Glass Cr Cu  1(A) 2.0 A 1.0(B) 0.7(B) 10(A) Ex. 4 Alumina Ti Cu 0(AA) 11.5  B 1.2(B) 1.0(B) 14(B) Ex. 5 Zirconia Ti Cu  0(AA) 1.5 B1.5(B) 1.8(B) 13(B) Ex. 6* Glass None None  2(A) Less than 1 B 3.5(C)2.5(C) 45(C) Ex. 7* Glass Al Cu 97(C) Non-peelable C 2.5(C) 3.0(C) — Ex.8* Glass Ti None  1(A) Non-peelable C 1.4(B) 1.4(B) — Ex. 9* Glass NoneCu  2(A) Non-peelable C 2.5(C) 4.0(C) — Ex. 10* Glass Ti Ni  3(A)Non-peelable C 1.0(B) 1.2(B) — Ex. 11 Glass Mo Cu  0(AA) 5.5 A 1.0(B)1.0(B)  2(AA) Ex. 12 Glass W Cu  0(AA) 4.3 A 1.0(B) 0.5(B) 10(A) Ex. 13Glass Mn Cu  0(AA) 10.0  B 1.0(B) 0.7(B)  4(AA) *denotes comparativeexamples. “—” in the table indicates impossible evaluation of thepattern formability of the embedded wiring layer due to “non-peelable”carrier.

TABLE 3 Chipping width Percent Peeling of defective resistanceextremely-thin in pattern of extremely-thin Releasability copper layerChemical formation of copper layer of carrier and other layerspenetration embedded Interlayer against developer Peel strength at sideends depth wiring layer Carrier Intermediate alloy layer (μm) (gf/cm)Rank (mm) (mm) (% by number) Ex. 14 Glass Cu—Mn (ratio 95:5) 0(AA) 5.0 A1.0(B)   0(AA)  4(AA) Ex. 15 Glass Cu—Mn (ratio 99:1) 1(A)    4.6 A1.0(B) 1.5(B) 17(B) Ex. 16 Glass Cu—Mn (ratio 90:10) 0(AA) 4.4 A 1.0(B)  0(AA)  3(AA) Ex. 17 Glass Cu—Mn (ratio 70:30) 0(AA) 4.8 A 1.0(B)  0(AA)  5(AA) Ex. 18 Glass Cu—Ag (ratio 95:5) 0(AA) 5.2 A 3.5(C)  0(AA) 15(B) Ex. 19 Glass Cu—Al (ratio 95:5) 100(C)    3.8 A 3.0(C)3.0(C) 30(C) Ex. 20 Glass Cu—Cr (ratio 95:5) 0(AA) 4.9 A 1.5(8) 1.2(B) 9(A) Ex. 22 Glass Cu—Ti (ratio 95:5) 0(AA) 4.5 A 1.0(8)   0(AA)  4(AA)Ex. 23 Glass Cu—Mo (ratio 95:5) 0(AA) 5.2 A 1.3(B) 1.2(B)  3(AA) Ex. 24Glass Cu—W (ratio 95:5) 0(AA) 5.3 A 1.0(B) 1.6(B)  8(A) * denotescomparative examples. The ratio is based on the number of atoms

TABLE 4 Thickness of Chipping width of release layer at extremely-thincopper Chemical Interlayer carrier end face layer and other penetration(Adhesive metal layer/Release (end-face thickness) layers at side endsdepth assisting layer) (nm) (mm) (mm) Ex. 25 Double-layer (Ti layer/Culayer) 0 Ex. 26 Double-layer (Ti layer/Cu layer) 0.3 0 (AA) 0 (AA) Ex.27 Double-layer (Ti layer/Cu layer) 0.9 0.5 (A) 0.2 (A) Ex. 28Double-layer (Ti layer/Cu layer) 1.5 15 (B) 1.5 (B) Ex. 29 Double-layer(Ti layer/Cu layer) 3 (same 1.5 (B) 5.0 (B) thickness as surface) Ex. 30Single-layer (Cu—Mn alloy layer, 0 0 (AA) 0 (AA) element ratio 95:5)

What is claimed is:
 1. A method for manufacturing a printed wiringboard, the method comprising: providing a copper foil including acarrier as a support; wherein the copper foil provided with a carriercomprises: a carrier; an interlayer disposed on the carrier; a releaselayer disposed on the interlayer; and an extremely-thin copper layerdisposed on the release layer, forming a wiring layer on a surface ofthe extremely-thin copper layer to prepare a coreless support includinga wiring layer; forming a build-up layer on a surface having the wiringlayer of the coreless support including the wiring layer; mounting anelectronic element on the coreless support to prepare a laminate;separating the laminate to prepare a multilayer wiring board includingthe build-up layer; performing selective etching to expose a wiringlayer of the multilayer wiring board; and providing an outer layer padon a surface of the wiring layer.